Friction discs particularly in high capacity aircraft disc brakes are subjected to extremely large heat loads as a result of energy transformation during the braking process causing the operating temperature of the friction discs to approach or exceed dangerously high temperatures. In the past, an entire friction disc or, at least, a significant portion thereof has been made of steel which cannot operate under the maximum brake temperatures reached without undesirable structural distortion and/or failure.
Relatively recent developments in aircraft high capacity disc brakes have led to the use of carbon or carbon based material for friction disc fabrication which material has the capability of withstanding much higher operating temperatures than steel without similar structural deterioration. However, a disadvantage of such a carbon or carbon based friction disc is that it has a characteristic strength weakness under tension and shear modes and, under high operating temperatures, is vulnerable to oxidation of the unswept friction surfaces thereof. The oxidation of the disc produces a corresponding undesirable physical deterioration of the same.
In view of the above, it will be recognized that a carbon or carbon based friction disc should not be subject to high localized stress in a tension or shear mode and oxidation of the friction disc should be avoided to a maximum extent.